1. Field of the Invention
The present invention is directed to a polarized relay, and more particularly to a polarized relay having an armature pivotally supported at its center to be swingable between two contact operating positions.
2. Description of the Prior Art
Polarized relays having a swingable armature are well known in the art, for example, as disclosed in U.S. Pat. Nos. 4,695,813, 4,703,293, and 4,499,442. Such prior art polarized relay comprises a coil block and an armature block which are fabricated as separate units and assembled together into a housing provided with a set of contacts and contact terminals extending therefrom. The coil block includes a coil bobbin having an excitation coil wound therearound, a core inserted therethrough, and coil leads extending from the ends of the excitation coil. A permanent magnet is disposed between the opposed legs of the core projecting on the ends of the coil bobbin. The armature assembly includes an armature and a set of movable springs with movable contacts which are held together and movable with the armature. The armature is pivotally supported on the casing so as to movable between two contacting operating positions of closing and opening the movable contacts with respect to the corresponding contacts on the side of the casing. Since such prior polarized relay requires to assemble the separately fabricated coil block and the armature block into the casing, a special care should be taken in order to place the coil block and the permanent magnet into an exact position in relation to the armature block in order to assure a predetermined magnetic gap between the core of the coil block and the armature of the armature block. Also, another care should be taken to isolate the movable springs from the coil by a distance sufficiently for effective electrical insulation therebetween. The above problems will be more prominent when the relay is to be miniaturized.